Disgust, disdain, and horror are distinct in theory, but overlap in practice. We recoil at emaciated, starving figures and feel disgust, largely because we feel horror. We do not feel disdain for them, but pity. Yet with fat, many people find it disgusting, and disdain is common. Horror and pity are less common. I am going to stick closely to disgust because it is one of Jonathan Haidt's six moral foundations. Paired with purity as its opposite, it is a moral axis that Haidt believes that Conservatives use much more often than liberals. He now calls it Sanctity/Degradation. His work is fascinating, and I largely agree with him. I will not summarise him here, but only point you to his own site, where he discusses these in detail.
I think he is largely wrong on this point. I believe he went wrong right from the start in his initial questionnaire. He asked if one had no other cloth in the house and the toilet needed cleaning, would it be acceptable to use an American flag? All groups generally said "no," but conservatives said so more often. There was also a question if the family dog had got hit by a car and killed, and there was no other food in the house, would it be okay to eat it for dinner? Almost everyone said "no," but there were more liberals who allowed it was okay. I will note that not all his questions were this extreme. It is good to have more ambiguous questions mixed with the extreme ones. Haidt concluded that liberals were less motivated by disgust. I think his choice of questions came from his liberal assumptions. He did not ask if one was out of toilet paper, would it be okay to use a newspaper that had a picture of Gandhi, or MLK, or Obama on it?
Similar arguments might be made about his other axes that liberals supposedly don't use, but conservatives do. I think he is largely right on the issue, but it is a nearer thing than he imagines. He has defined some things as authority, some things as loyalty, and so forth, that might be defined otherwise. There are authorities liberals defer to that he hasn't asked about.
I think liberals and conservatives are pretty even in their use of disgust as a guiding moral principle. This is of more than theoretical importance because disgust is malleable, and changes over time. You know it in everyday life, hearing people say "I used to be disgusted by blank until I got a job working as a blank." It can come back, especially if it is associated with trauma. People were disgusted by blood and mutilated flesh and death until the went to a war zone, where they got more used to it than the y ever wanted. Then they came back and disgusted again, though in a different way, because of their associations. We are disgusted by some foods until we try them because of hunger or social pressure, then come to like them. Many of us, particularly females, thought the sexual act sounded pretty disgusting when we first got a clear picture of what it it actually was, but we, uh, got over that. I have words I don't use because they disgust me. I have others, like crap, that used to disgust me but I now use. I enjoy foods I used to shudder at. People who found smoking unattractive but put up with it no longer do.
Someone else might want to do a post on how these changes happen, but I'm not that fascinated by the process, only by the fact that it does occur. I am not strongly motivated by disgust myself. I have things that disgust me, but I try to step back and say "What's the real damage here? What's the real problem here?"
Kirsten Gillibrand, discussing what she would do if elected president “The first thing I would do is Clorox the oval office. ” That’s disgust talking.
Haidt can tell you how disgust manifests in conservatives, but I'd like to illustrate how it manifests in liberals, because in the academic conversation, that seems to be missing. There is the disgust of the newspaper with the photos, above. Environmentalism is built on disgust, as the political cartoons reveal. It goes beyond being disgusted by smoke or smog, and includes mud, smelliness, and the many goops of nature that make a place look unattractive. Possible toxins that are invisible, such as PCB's , get a pass. It makes the people who actually work in environmental cleanup and prevention a little crazy sometimes, to watch people get excited about controlled logging because it looks ugly rather than aquifers that are out-of-sight. Bogs, shallow ponds, dead jellyfish - or on the other side of the purity question the idea of pristine wilderness (now there's a discussion) can get people worked up about mining, drilling, building, largely because of appearance, not danger or pollution.
Gun control may be largely motivated by fear, but disgust at hunting is not that far beneath the surface. Not with all, but with some. Controllers aren't that willing to give ground to gun owners even in the face of overwhelming evidence that universal background checks or banning of certain weapons simply has no effect. They don't like hunting, and they don't like guns.
There are vegetarians on both the left and right, but there are more on the left, and if you let people talk, I'd say about half of them reveal that disgust at butchery and eating flesh is prominent. If you ask them to tell their story of how they became vegetarians, it's even more. Reasons to sustain are not always the same as reasons to adopt, but there is continuity. There is sometimes something rather disquieting about (some of) them as well. Do they not actually like large swaths of humans? Opposition to GMO's is not merely fear of the unknown or fear of risk. If you go over and read the actual complaints, you will find disgust is very powerful.
It shows up strongly in discussion of Trump. As in many things, he brings to the fore many unattractive motives of his opponents that they were more able to keep contained with Bush, McCain, Romney.
Criticism of Trump is sometimes physical, focusing on his hair, his voice, his general ickiness. I wonder how it all fits with the concept of embarrassment as a moral disqualifier. It shouldn't be that deeply related, but the complaints about Trump's vulgarity come as a package with shudders about his hair, and his facial expressions. Well, small sample size on that: on my FB feed and where I work there are plenty of mini-rants about how infuriating it is to listen to him and look at him - grown women talking like sophomore girls. Worse, that is what attracts all their energy, though they are educated enough to develop a coherent argument based on policy and principles. Lord knows Trump supplies enough material to not have to be distracted into discussing how he is just such an impossible man. I don't get it.
Partof it is because of mere imbalance in reporting – things like “You’d better put some ice on that” are known mostly only to conservatives – but because these things arouse anger at their unfairness rather than disgust. The one accusation that caused Clinton the most trouble had some details that might arouse disgust. That’s part of why they had legs. I thought Trump's "grab 'em by the pussy" was indeed an offensive thing to say, in any context. Because of the disgust, Trumps’s critics miss that the comment was largely one of amazement, and that it is in fact accurate that not only do some men behave this way, but so do some women. There was no hint of advocating forcing oneself on unwilling women. But feelings of disgust overwhelm reason and stick in the memory.
Plus, Bill Clinton was cute. That has a lot to do with whether people are disgusted.